Mobile robots that move while autonomously determining a movement path are required to generate an environment map using measurement data obtained from a vision sensor such as a stereo camera or a range sensor, unless the environment map is provided in advance. Additionally, each mobile robot is required to repeatedly performing processing for generating an environment map along with the movement of the robot, since the surrounding environment of the mobile robot changes every moment along with the movement of the mobile robot.
For example, a walking motion of a legged mobile robot is achieved such that areas on which the foot soles can be placed are determined referring to an environment map, and landing positions of the foot soles are sequentially mapped out. Accordingly, the legged mobile robot needs to generate an environment map that allows discrimination between an area belonging to a floor surface on which the foot soles can be placed, and an obstacle area other than the area. A specific example of the environment map is an environment map obtained by detecting a plane group from a three-dimensional position data set calculated based on a parallax image obtained from a vision sensor such as a stereo camera or a range sensor, and based on measurement information such as distance information on a distance from a measurement object. Patent Document 1, for example, discloses a technology in which a plurality of planes including the floor surface in contact with the foot soles of a legged mobile robot are detected by calculating a plane parameter using a three-dimensional position data set, and an environment map specifying an obstacle area and a movable area is generated using the detection results of the plurality of planes.    [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2005-92820    [Patent Document 2] Japanese Unexamined Patent Application Publication No. 02-224986